Vertebral body replacement

ABSTRACT

This invention concerns a vertebral body replacement element to be inserted into an intervertebral space, thus supporting the spinal column of a patient. The present invention further concerns a system and method for expanding and distracting a vertebral body replacement into and within the spinal column of a patient.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57. Thisapplication is a continuation application of U.S. application Ser. No.11/937,242, filed Nov. 8, 2007, which claims the benefit of U.S.Provisional Application No. 60/864,857, filed Nov. 8, 2006, each ofwhich is hereby incorporated by reference herein.

BACKGROUND

1. Field

The present invention generally relates to a vertebral body replacementto be inserted into an intervertebral space, thereby supporting thespinal column of a patient. The present invention further relates to asystem and method for expanding and distracting a vertebral bodyreplacement element into and within the spinal column of a patient.

2. Description of the Related Art

Back pain is one of the most significant problems facing the workforcein the United States today, is a leading cause of sickness-relatedabsenteeism, and the main cause of disability for people between theages of 19 and 45. Back pain can occur from pinching or irritating aspinal nerve, compression of the spine, vertebral shifting relative tothe spinal cord axis, and formation of bone spurs. The most common causeof disabling back pain, however, generally stems from trauma to avertebral disc, such as from mechanical shock, stress, tumors, ordegenerative diseases. In many cases, the disc can become permanentlydamaged or degenerated, such that the preferred treatment necessitatespartial or total excision and replacement of the damaged disc.

Traumatic injury to a vertebral disc that is not removed frequently canpromote scar tissue formation. Such scar tissue typically is thickerthan the healthy tissue, such that the disc continues to progressivelydegenerate, lose water content, and can stiffen and become significantlyless effective as a shock absorber. Eventually, the disc can deform,herniate, or collapse, eliminating the flexibility of the spinal column,and potentially leading to further degeneration or damage to othervertebral discs of the spinal column. At such a point, the only optionis for the damaged disc to be partially or completely removed.

When the disc is partially or completely removed, generally it isnecessary to replace the excised material to prevent direct contactbetween the boney surfaces of the adjacent vertebrate on either side ofthe removed disc. For example, U.S. Pat. No. 6,824,565 of Muhannadiscloses a vertebral spacer that is inserted between adjacentvertebrate to provide restorative force and function as a shock absorberbetween the adjacent vertebrate. Another alternative approach has beento insert a “cage” that can maintain a space occupied by the removeddisc to prevent the vertebrate from collapsing and impinging upon thenerve roots of the spine. Still further, spinal fusion has been used torestrict motion and stabilize patients' spines by fusing adjacentvertebrate together. This generally can reduce mechanical back pain bypreventing the now immobile vertebrate from impinging on a spinal nerve;however, such stability and pain reduction generally is created at theexpense of spinal flexibility and motion. In addition, many conventionaltechniques for disc repair and replacement can be limited in terms oftheir size or configuration and thus generally are not designed toaccommodate variations in size of the gap resulting from the excising ofthe vertebral disc material. Further, conventional techniques oftencannot accommodate expansion or growth of the spine, frequentlyrequiring replacement of the vertebral spacers with other, differentsize spacers.

Accordingly, it can be seen that a need exists for a vertebral bodyreplacement and system and method of implanting such a vertebral bodyreplacement that addresses the forgoing related and unrelated problemsin the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are perspective illustrations of various alternativeembodiments of the vertebral body replacement member according to theprinciples of the present invention.

FIG. 2 is an exploded perspective illustrating the installation of thevertebral body replacement member such as illustrated in FIGS. 1A or 1Bwithin the spinal column of a patient.

FIG. 3 is a perspective illustration, illustrating the distraction ofthe intervetebral body replacement member according to the principles ofthe present invention positioned between adjacent vertebrate of thepatient's spine to enable insertion of a spacer therebetween.

DETAILED DESCRIPTION

As generally illustrated in FIGS. 1A-1C, the present invention isdirected to an vertebral body replacement member or elements forinsertion into an intervertebral space or gap between vertebrae of apatient's spine to replace substantially all of a vertebral disc orvertebrae that has been excised or removed due to damage or degenerationof the disc. The vertebral body replacement member of the presentinvention generally is useful to replace a vertebral disc that hasdegenerated due to traumatic injury, vertebral displacement, disease(i.e., autoimmune disease, rheumatoid arthritis, etc.), or any otherpathological condition of the spinal column that may injure or shift theintervetebral discs. The vertebral body replacement member of thepresent invention provides support to the adjacent vertebrae of thepatient's spine to help maintain the separation between the vertebrae,while also preserving the natural curvature of the spine and furtherenabling regenerative bone growth and adjustment of the intervertebralspacing between the adjacent vertebrae to accommodate growth orexpansion therebetween.

It is generally contemplated that the vertebral body replacement memberof the present invention can be made from any bio-compatible orphysically inert material or combination of such materials having themechanical strength capable of maintaining the intervetebral spacebetween adjacent vertebrae, as indicated in FIGS. 2 and 3, withoutimpinging upon nerves and/or restricting movement and further bonegrowth or regeneration of the spinal column discs adjacent theintervetebral space in which the present invention is mounted. Examplesof such materials can include bone, such as bone sections from a femuror other bones of the patient or from donors, metal materials such astitanium, titanium alloys, stainless steel, chrome, cobalt, and other,similar materials, as well as various polymeric materials such as methylmethacrylate (MMA), urethane, polyacetal material, reinforced polymerssuch as carbon fiber or polyether keytone, polycarbonates,polypropylene, polyamides, and silicone based polymers as generallyunderstood in the art.

As illustrated in FIGS. 1A-3, the vertebral body replacement member ofthe present invention generally includes a telescoping construction,including an upper section and a lower section. The upper section andlower section of the component engage or interface via a sliding jointwhich allows relative linear motion. Assembly, adjustment, and removalof the vertebral body replacement member is enhanced with the slidingjoint because the sections advantageously move more freely than withother attachment or interfacing means. While alternate attachment orinterfacing means may be available, an acceptable alternate does notinclude a threaded means. The upper and lower sections can be formed invarious configurations including generally cylindrical having asubstantially circular cross section as illustrated in FIGS. 1A and 2;cylindrical with a substantially oval cross-section as illustrated inFIG. 1B; or can be formed in square or rectangular configurations asgenerally illustrated in FIG. 1C and 3. Among other functions, thenon-circular embodiments have the added benefit of restrictinglongitudinal rotation relative to the axis of linear motion between theupper and lower sections. An alternate means of restricting longitudinalrotation between the upper and lower sections from those disclosed inFIGS. 1B and 1C would be a key and keyway interface. In someapplications, restriction of longitudinal rotation is desired and isaccomplished by the non-circular embodiments. The circular configurationis advantageous in that although longitudinal rotation is not required,is possible, while providing relative linear motion of the upper andlower sections. Further, with the top and bottom surfaces angled orcontoured as discussed below, restricting longitudinal rotation of theupper and lower sections is desired. Each of the upper and lowersections further generally will include an open-ended body formed from abio-compatible or physically inert material as discussed above, and oneof the sections, for example the upper section, will be formed with atleast a portion of its body having a slightly smaller diameter orcross-sectional area than the lower section so as to telescope into andout of the open upper end of the lower section as indicated in FIGS.1A-1C. It will, however, also be understood that the upper and lowersections can be formed with the lower section telescoping into and outof the upper section as needed or desired.

The open ended structures of the upper and lower sections furthergenerally will define a space or cavity within the vertebral bodyreplacement member as the two sections are brought together. The uppersection generally will include a substantially flat top that further caninclude channels or openings formed therein, and, as illustrated inFIGS. 1A and 1B, further can include a series of teeth or serrationsformed about the side edges of the upper or top portion of the uppersection to help secure it against an adjacent upper vertebrae. The lowersection typically has a similar construction, with an open upper end, aclosed, substantially flat bottom surface, and further generallyincludes slots or openings formed in its bottom or base plate. The lowersection also can include series of teeth or serrations formed about theside edges of its lower or bottom base plate to help engage and fix thelower section to the lower vertebrae of the patient's spine in which itis mounted. The top and bottom surfaces of the upper and lower sections,respectively, additionally can be angled or contoured as needed tosubstantially match the contour of the adjacent upper and lowervertebrae on which the sections are mounted or engaged.

The openings formed in the top and bottom portions of the upper andlower sections, respectively, of the vertebral body replacement member,as well as growth openings formed in the side walls thereof, such asindicated in FIG. 1C, provide areas or points of access for bone to growand expand into the surrounding tissue about the patient's spine tofurther help secure the vertebral body replacement member within thepatient's spine and to foster or facilitate regeneration and additionalbone growth. The telescoping construction of the vertebral bodyreplacement member further enables the vertebral replacement member toexpand or extend as needed to accommodate such additional orregenerative bone growth and to enable further adjustment of the spacingprovided by the vertebral body replacement member as needed to fit theintervetebral space created by the excising or removal of part or theentirety of the damaged vertebral disc.

As further illustrated in FIGS. 1-3, the upper and lower sections eachgenerally include a large slotted opening formed through the side wallor walls of the upper and lower sections of the vertebral bodyreplacement member. This opening enables the insertion and packing ofbone material within the cavity defined between the upper and lowersections of the vertebral body replacement member after implantation orplacement of the vertebral body replacement member within the patient'sspine. Such implanted bone material can then fuse to and grow with theexisting remaining vertebrae of the patient, expanding out through theopenings formed in the top, bottom, and side walls of the upper andlower sections, respectively, of the vertebral body replacement memberand into contact with the adjacent upper and lower vertebrae and thetissue surrounding the patient's spine.

Still further, as illustrated in FIG. 3, the upper and lower sections ofthe vertebral body replacement member further generally will include adistraction slot or similar opening for receiving a distracterinstrument or tool therein. Alignment of the distraction instrument ortool with the distraction slot is preserved because of the restrictionof relative longitudinal rotation between the upper section and lowersection in the non-circular embodiments (and the circular embodimentwith keyways or other restrictive rotational restraints). The ends ofthe distracter instrument will be introduced into the distraction slotsformed in the upper and lower sections for placement of the vertebralbody replacement member within the vertebral space or excised areabetween the adjacent vertebrae and thereafter expanding the sections asneeded by causing the upper and lower sections to telescope or moveoutwardly away from each other so as to expand the intervertebral bodyreplacement member at needed to fill the intervertebral space.

In addition, as illustrated in FIGS. 1C-3, one or more spacers also canbe mounted between the upper and lower sections of the vertebral bodyreplacement member as needed. The spacers generally will be made fromthe same or a compatible material as the upper and lower sections of thevertebral body replacement member and typically will be of a similarconfiguration and/or size as the upper and lower sections so as to fittherebetween without substantially overlapping the side edges of theupper and lower sections and, provide a more mechanically robust andrugged structure due to the superior load carrying abilities of a nestedstructure in compression having a large load bearing surface. Forexample, as illustrated in FIGS. 1B, 2 and 3, the upper section of thevertebral body replacement member can include a bottom portion formedwith a reduced area or diameter that is adapted to be received andtelescope into the open upper end of the lower section. The spacers canbe of a similar size and configuration as the upper and lower sectionsso as to fit over this recessed portion of the upper section asindicated in FIGS. 2 and 3. The spacers also can be provided with teethas needed to help secure the spacers in place within the intervertebralspace.

The spacers typically will be inserted as needed after implantation ofthe vertebral body replacement member within the intervetebral space, byengagement of the upper and lower sections of the vertebral bodyreplacement member by the distraction tool and expansion thereof, so asto create a gap in which the spacer or spacers can be inserted.Thereafter, as the distraction instrument is closed, the upper and lowersections of the vertebral body replacement member will be broughttogether, sealing into engagement with each other and with any spacerscontained therebetween. Thereafter, the distraction tool or instrumentcan be removed and the surgical opening in the patient's back closed.Still further, if additional spacers are needed, the distraction toolcan be engaged with the slots in the upper and lower slots and the upperand lower sections further separated to enable implantation of aadditional spacers as needed.

The present invention thus provides a simple device, typically made froma single, biocompatible material with minimal parts and generallyutilizing only a minimal presences of screws, if at all, or similarfasteners to attach the upper and lower sections of the vertebral bodyreplacement member to the adjacent vertebrate of the patient. Thevertebral body replacement member further is radiolucent and expandable,and any distraction required is done by distracting the deviceinternally through the engagement of the distraction instrument with theslotted openings in the upper and lower sections thereof, such thatthere is no distraction or engagement of screws that could damage bone.The growth openings formed in the top, bottom and side walls of theupper and lower sections, respectively, further enable bone growth outof the vertebral body replacement member and into the surrounding boneand tissue to help promote healing and more natural freedom of movement,while maintaining the intervetebral space and preventing collapse of thepatient's spine.

It will be understood by those skilled in the art that while theforegoing has been described with reference to preferred embodiments andfeatures, various modifications, variations, changes and additions canbe made thereto without departing from the spirit and scope of theinvention.

1. (canceled)
 2. (canceled)
 3. A method for implanting a vertebral bodyreplacement device, comprising: attaching a distracter instrument to avertebral body replacement device, wherein the vertebral bodyreplacement device comprises a first component having a first end and anopen second end and a second component having a first section and asecond section, the first section having a third end and a fourth endand the second section extending from the fourth end, the second sectionhaving a smaller cross-sectional area than the first section andconfigured to telescope within the open second end of the firstcomponent, and wherein the distracter instrument comprises a first armconfigured to engage the first component and a second arm configured toengage the second component; delivering the vertebral body replacementdevice to a location in a patient's spine using the distracterinstrument; expanding the vertebral body replacement device by movingthe first and second arms of the distracter instrument away from eachother causing the first and second components to move outwardly awayfrom each other; and inserting a spacer between the first component andthe first section of the second component.
 4. The method of claim 3,wherein the spacer comprises a split ring.
 5. The method of claim 3,wherein the first and second components are non-circular.
 6. The methodof claim 3, wherein attaching the distracter instrument to the vertebralbody replacement device comprises inserting ends of the distracterinstrument into distraction slots in the first and second components. 7.The method of claim 3, wherein inserting the spacer comprises disposingthe spacer around the second section of the second component.
 8. Themethod of claim 3, further comprising selecting the spacer from one of aplurality of spacers having different lengths.
 9. The method of claim 8,wherein a length of the vertebral body replacement device can beadjusted by selecting a spacer having a different length.
 10. The methodof claim 3, wherein delivering the vertebral body replacement device tothe location in the patient's spine comprises positioning the vertebralbody replacement device such that the first end contacts a firstvertebral body and the third end contacts a second vertebral body. 11.The method of claim 10, wherein the first end and third end comprise aseries of teeth or serrations configured to secure the first and secondcomponents to the first and second vertebral bodies, respectively. 12.The method of claim 3, wherein inserting the spacer comprisespositioning the spacer such that one end of the spacer abuts the secondend and an opposite end of the spacer abuts the fourth end.